A long time ago when Rhett and Scarlett (littermates, now 3 years
old, but adopted at about 9 weeks) were learning how to play, how
to scratch their toys, learning everything, I would praise them for
scratching their posts and cat tree and the turbo scratcher that
everyone loves. Over time Rhett learned that if he scratched the
turbo scratcher I'd rub his ears and praise him. Then somehow it
evolved into if he rolled the ball around the track, I'd somehow
react, either giggling, or just talking to him. Now it's turned in
to this scenario every day:

Rhett bats the ball around the track. Comes to me if I'm working on
the computer for pets.

Mommy is working on computer and not paying any attention to
kitties, Rhett goes to bat the ball, comes to Mommy for pets. If
Mommy is busy and doesn't notice, Rhett bats ball again and comes
to Mommy for pets.

Its now gotten to the point that if I hear the ball going around, I
better give him attention for doing it when he comes over to me,
otherwise he'll put his paws up on the table and reach up to nibble
my hands as I type.

What a smart cat.